Ceramics, metals, and synthetic resins which are excellent in durability, heat resistance, and mechanical strength are widely used for various applications of household electrical appliances, electronic parts, mechanical parts, automotive parts, and the like. There may be the case where these members are used upon being adhered or complexed with an elastomer member having excellent flexibility depending upon an application, a part constitution, a use method, and the like for the purpose of immobilizing on other structural members or purpose of impact absorption, breakage prevention, sealing, or the like.
As such an elastomer member, a styrene-based thermoplastic elastomer which is excellent in flexibility and dynamic properties, and further molding processability may be suitably used. The styrene-based thermoplastic elastomer as referred to herein refers to a block copolymer having a polymer block containing an aromatic vinyl compound unit and a polymer block containing a conjugated diene compound unit, or a hydrogenation product thereof.
However, since the styrene-based thermoplastic elastomer is a material with low polarity, it is not sufficient in adhesive force to ceramics, metals, or the like, so that there is involved such a problem that it is difficult to achieve melt adhesion as it is. For that reason, in order to allow the styrene-based thermoplastic elastomer to adhere to a ceramic or a metal, there are disclosed methods of applying an adhesive, or subjecting the surface of a ceramic, a metal, or a synthetic resin to a primer treatment in advance (see PTLs 1 to 6).
However, the methods disclosed in PTLs 1 to 6 involve such a problem that not only the process is complicated, but also the productivity is low, an that the production costs become high.
Against such a problem, there is disclosed a thermoplastic polymer composition including a styrene-based thermoplastic elastomer and polyvinyl acetal, the thermoplastic polymer composition having excellent adhesiveness to a ceramic, a metal, or a synthetic resin (see PTL 7). It is possible to allow this thermoplastic polymer composition to adhere to a ceramic, a metal, or a synthetic resin only through a heat treatment, without applying an adhesive or performing a primer treatment.